New plugin: Vendure-plugin-primary-collection

[martijnvdbrug]

Is your feature request related to a problem? Please describe.

To construct breadcrumbs and URL's it's useful to have a primary collection for each product, in case a product is part of multiple collections.

Describe the solution you'd like

• I would like the field Product.primaryCollection to return the primary collection of a product
• The primary collection of a product is the collection that is the highest placed collection in Vendure (Collection's are sortable in Vendure, and it's a good practice to sort by importance).
• E2e test: Create 2 categories, place product in both categories, querying product.primaryCollection should always be the highest placed collection.
• Code has already been used in another project, ready to copy/paste. See below for snippet.

Additional context

Shop API schema:

  extend type Product {
    primaryCollection: Collection
  }

Resolver code (feel free to change or improve where necessary):

import { Parent, ResolveField, Resolver } from "@nestjs/graphql";
import {
  Collection,
  CollectionService,
  Ctx,
  RequestContext,
  Product,
} from "@vendure/core";

@Resolver("Product")
export class PrimaryCollectionResolver {
  constructor(private readonly collectionService: CollectionService) {}

  @ResolveField()
  async primaryCollection(
    @Ctx() ctx: RequestContext,
    @Parent() product: Product,
  ): Promise<Collection | null> {
    const collections = await this.collectionService.getCollectionsByProductId(
      ctx,
      product.id,
      true,
    );
    const collectionsExcludingParents = collections.filter(
      (coll) =>
        !collections.find((childColl) => childColl.parentId === coll.id),
    );
    return collectionsExcludingParents.reduce<Collection | null>(
      (acc, val) => {
        if (!acc) {
          return val;
        }
        if (val.position < acc.position) {
          return val;
        }
        return acc;
      },
      null
    );
  }
}

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